1. Field of Invention
Embodiments of the invention relate generally to memory devices and more specifically to data management in non-volatile memory devices, such as NAND memory devices.
2. Description of Related Art
Electronic systems, such as computers, personal organizers, cell phones, portable audio players, etc., typically include one or more memory devices to provide storage capability for the system. System memory is generally provided in the form of one or more integrated circuit chips and generally includes both random access memory (RAM) and read-only memory (ROM). System RAM is typically large and volatile and provides the system's main memory. Static RAM and Dynamic RAM are commonly employed types of random access memory. In contrast, system ROM is generally small and includes non-volatile memory for storing initialization routines and identification information. Non-volatile memory may also be used for caching or general data storage. Electrically-erasable read only memory (EEPROM) is one commonly employed type of read only memory, wherein an electrical charge may be used to program data in the memory.
One type of non-volatile memory that is of particular use is a flash memory. A flash memory is a type of EEPROM that can be erased and reprogrammed in blocks. Flash memory is often employed in personal computer systems in order to store the Basic Input Output System (BIOS) program such that it can be easily updated. Flash memory is also employed in portable electronic devices, such as wireless devices, because of the size, durability, and power requirements of flash memory implementations. Various types of flash memory may exist, depending on the arrangement of the individual memory cells and the requirements of the system or device incorporating the flash memory. For example, NAND flash memory is a common type of flash memory device.
In systems or devices that use flash memory devices, the system, device, or flash memory device may include a controller that stores programs (e.g., firmware) and controller data in a portion of the flash memory device being controlled. During operation, the controller may load the programs and other data from the flash memory device and execute the programs to operate the memory device. Because these programs and data are stored in the flash memory device, the controller programs and data are subject to the same failure rate of the flash memory device. If a memory device fails, so that the controller programs and/or data is lost or inaccessible, the controller may no longer be able to control the memory device, causing a failure of the device and possible data loss of other data stored on the device.